Photographic material

ABSTRACT

A COMPOSITE INTEGRAL LIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL FOR FORMING COPIES BY MEANS OF THE DIFFUSION TRANSFER PROCESS COMPRISING IN SUCCESSIVE ORDER A TRANSPARENT FLEXIBLE SUPPORT SHEET AND IMAGE-RECEIVING LAYER COMPRISING DEVELOPMENT NUCLEI, A PIGMENT LAYER CONTAINING AN OPAQUE WHITE OR COLORED PIGMENT DISPERSED IN A HYDROPHILIC COLLOID BINDER, WHEREIN THE PIGMENT AND THE BINDER OF THE PIGMENT PARTICLES ARE PRESENT IN AN AMOUNT OF FROM 7 TO 25 G. PER SQ. M. AND OF FROM 0.5 TO 4 G. SQ. M., RESPECTIVELY, AND A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, THE MAXIMUM DEVELOPED REFLEX DENSITY OF WHICH IS EQUAL TO OR LOWER THAN 0.8. A PHOTOGRAPHIC METHOD USING SUCH MATERIAL IS ALSO DISCLOSED. THE DEVELOPED MATERIAL HAS A POSITIVE IMAGES IN THE IMAGE-RECEIVING LAYER WHICH IS VISIBLE DIRECTLY THROUGH THE TRANSPARENT SUPPORT SHEET, TOGETHER WITH A NEGATIVE IMAGE IN THE EMULSION LAYER WHICH IS HIDDEN FROM THE POSITIVE IMAGE BY MEANS OF THE INTERVENING PIGMENT LAYER SO THAT THE MATERIAL CAN BE EXPOSED, DEVELOPED AND VIEWED IN THE FORM OF AN INTEGRAL ASSEMBLY WITHOUT SEPARATION OF THE PARTS THEREOF.

United States Patent 3,740,220 PHOTOGRAPHIC MATERIAL Louis Maria DeHaes, Edegem, Emiel Alexander Hofman, Mortsel, and Hugo Karel Gevers,Edegem, Belgium, assignors to Agfa-Gevaert, Mortsel, Belgium No Drawing.Filed Dec. 5, 1969, Ser. No. 882,737 Claims priority, application GreatBritain, Dec. 6, 1968, 58,152/ 68 Int. Cl. G03c 5/54 US. CI. 96-29 R 12Claims ABSTRACT OF THE DISCLOSURE A composite integral light-sensitivephotographic material for forming copies by means of the diflusiontransfer process comprising in successive order a transparent flexiblesupport sheet and image-receiving layer comprising development nuclei, apigment layer containing an opaque white or colored pigment dispersed ina hydrophilic colloid binder, wherein the pigment and the binder of thepigment particles are present in amount of from 7 to 25 g. per sq. In.and of from 0.5 to 4 g. sq. m., respectively, and a. light-sensitivesilver halide emulsion layer, the maximum developed reflex density ofwhich is equal to or lower than 0.8. A photographic method using suchmaterial is also disclosed. The developed material has a positive imagein the image-receiving layer which is visible directly through thetransparent support sheet, together with a negative image in theemulsion layer which is hidden from the positive image by means of theintervening pigment layer so that the material can be exposed, developedand viewed in the form of an integral assembly without separation of theparts thereof.

The present invention relates to a photographic lightsensitive compositesheet material and to a method of producing images according to thesilver complex diffusion transfer process wherein such material is used.

The photographic light-sensitive composite sheet material according tothe present invention successively comprises a flexible transparentsupport sheet, an image-receiving layer comprising substances forpromoting the conversion of complexed diffusing silver halide to form avisible image (these substances are further on called developmentnuclei), a pigment layer containing an opaque white or coloured pigmentand a hydrophilic colloid binder, wherein the pigment and the binder ofthe pigment particles are present in amounts of from 7 to 25 g. sq. m.and of from 0.5 to 4 g. per sq. m. respectively, and a light-sensitivesilver halide emulsion layer, the maximum developed reflex density ofwhich is equal to or lower than 0.8.

The present invention also relates to a method of producing aphotographic diflusion transfer copy comprising the steps of image-wiseexposing the light-sensitive silver halide emulsion layer of aphotographic composite sheet material as described above and treatingthis material in the presence of a developing compound, a complexingagent for silver halide and an alkaline substance with an aqueousliquid. The diffusion transfer copy thus obtained is viewed through thetransparent support and the low density negative image is thencompletely screened from the eye of the pigment layer. At the emulsionside of the copy only a very faint and not disturbing negative image isvisible.

When a silver halide emulsion layer is applied as described above, theuse of high amounts of pigment particles in the pigment layer can beavoided, so that the diffusion of the complexed silver halide from thenonexposed areas of the emulsion layer is promoted. A diifusion transferimage showing a sufliciently high maximum 'ice density, mostly amountingto about 1.5, can be produced thereby in spite of the nature of thesilver halide emulsion layer.

The requirements of amixmum. developed reflex density of 0.8 of thesilver halide emulsion layer may be complied with by applying the liquidsilver halide emulsion in such a proportion that only a restrictedamount of silver halide particles is present per surface unit of thelight-sensitive material. According to another technique a considerableamount of pigment particles and/or screening dyes may be incorporatedint-o the silver halide emulsion layer. According to a preferredembodiment, however, silver halide emulsions are used, which have theinherent property of being developable only to a low maximum densityafter exposure. This may be achieved by producing rather large silverhalide grains. Two or more techniques for producing a silver halideemulsion layer complying with the requirements of the present inventionmay be combined.

Any type of silver halide is suitable for preparing the emulsion layer,provided the silver halide grains are capable of being developed andcomplexated in the exposed and non-exposed areas respectively with therapidity required in diffusion transfer processess. The silver halideemulsion used may be a low-sensitive or a high-sensitive emulsion andmay have either a steep gradation for the production of a line copy or arather soft gradation for the production of a continuous tone image. Forthe reproduction of a line original often a low-sensitive silverchloride emulsion having a steep gradation is used, Whereas for thereproduction of a continuous tone original preferably a silverbromo-iodide emulsion having a soft gradation is used. Provided thesensitivity of the silver halide emulsion is sufliciently high, thephotographic composite sheet material according to the present inventionis especially suitable for making aerial photographs.

The pigment layer preferably contains white pigment particles. Bariumsulphate and titanium dioxide are especially suitable for this purpose.The size of the pigment particles is of no great importance for thepurpose of the present invention. Coarse as well as extremely finegrains are suited. The particle size: mostly is comprised between 0.05and 0.5,u. In general, optimal results are obtained with an amount of 10to 20 g. of pigment and of 1 to 3 g. of hydrophilic colloid per sq. m.Gelatin is often used as the hydrophilic colloid binder of the pigmentparticles. However, other hydrophilic colloids and mixtures of two ormore types of hydrophilic colloids may be used. So, a mixture of aprotein, e.g. gelatin, and a hydrophilic colloid, which in the alkalinemedium wherein the production of the diffusion transfer image takesplace hardens said protein, is especially suited as a binder of thepigment particles. Hydrophilic colloids of this type are comprised inthe class of compounds designated as latent hardeners of said proteins.Suitable hydrophilic colloids of this type are addition products of highmolecular weight hydroxyl group-containing compounds with acrolein,described in the United States patent specification 3,382,077 andespecially water-soluble hydroxyalkyl esters of alginic acid,particularly propylene glycol esters of alginic acid, described in theUnited States patent specification 3,378,373.

The image-receiving layer present between the pigment layer and thetransparent support sheet may be constituted by development nucleiapplied by vacuum coating but preferably is a hydrophilic colloid layercontaining development nuclei. The hydrophilic colloid binder ispreferably gelatin, although the gelatin may be replaced at least partlyby other hydrophlic colloids. The development nuclei may be small metalparticles but preferably are sulphides of heavy metals such as thesulphides of antimony, bismuth, cadmium, cobalt, lead, nickel, silver,

and zinc. Of course, other types of development nuclei can be used.Further details on the composition and the thickness of theimage-receiving layer as well as on the concentration of the developmentnuclei are superfluous. In this respect, reference is made to the veryextensive art literature, including the patent literature. Theimagereceiving layer may be applied, directly or indirectly by means ofa suitable subbing layer, to the flexible transparent support sheet.

For the purpose of the present invention the support has to besufiiciently transparent to permit the diffusion transfer image producedin the image-receiving layer to be viewed through the support. So, apaper sheet that has been made transparent can be used. An especiallysuitable paper support is the so-called pergamin paper that owes itstransparency to hydration and mechanical treatment at the preparationstage. Preferably, however, the transparent support sheet of thecomposite sheet material according to the present invention is ahydrophobic synthetic film support having a rather small thickness thatis preferably comprised between about 0.05 and 0.2 mm. Suitablehydrophobic synthetic polymers are cellulose esters, e.g. cellulosetriacetate, polyesters e.g. polyethylene terephthalate, polystyrene, andcopoly(vinyl chloride/vinyl acetate).

The photographic material according to the present invention maycomprise all kinds of additional layers, e.g. an antihalation layer, atop layer for protecting the silver halide emulsion layer againstabrasion, or for completely screening the negative image from the eye,one or more intermediate layers to improve the adherence between twolayers, or to facilitate the diffusion of some substances from one layerto the other, an antistatic layer, which is preferably applied to thefree rear side of a hydrophobic film support, etc.

According to a preferred embodiment the rear side of the transparentsupport is provided with a matting layer, e.g. a gelatin layercontaining silica particles. Such a layer exerts an antistatic andanticurling effect on the photographic material, gives the diifusiontransfer copy produced a more pleasant appearance, and allows to writeon the material more easily.

The layers of the photographic sheet material may be applied accordingto Whatever technique known in the art, e.g. by dip-coating, reverseroll-coating, or by spraycoating.

The photographic composite sheet material may contain all kind ofingredients, e.g. sensitizers, stabilizers, plasticizers, hardenersincluding latent hardeners, e.g. the hydrophilic colloid bindersreferred to above, developing agents, preservatives for developingagents complexing agents for silver halide, alkali-releasing substances,imagetone improvers, anti-silver sludge agents, anti-yellowing agents,anti-staining agents, alkali-consuming substances, dispersing andwetting agents etc. The use of these ingredients in photographicmaterials for producing diffusion transfer copies is generally known inthe art. For more details thereon reference is made to the veryextensive art literature including the patent literature.

The incorporation of developing substances, especially of hydroquinoneand a S-pyrazolidinone developing agent, into at least one layer of thecomposite sheet material is a preferred embodiment of the presentinvention. In many cases the total amount of developing substances isincorporated into the photographic material, so that the processingliquid is reduced to a mere alkaline liquid that is substantially freefrom developing agents, and consequently has better keeping properties.

In carrying out the method of the present invention the silver halideemulsion layer of the photographic composite sheet material isimage-wise exposed to visible light or to a high energetic radiationbeam, e.g. an electron beam, X-rays, 'y-rays, light produced by a laseretc. The image-wise exposure is preferably carried outreflectographically by placing the original in contact with the emulsionside of the composite sheet material, and transmitting the exposing raysthrough said material. However, exposure in a camera is also possible.

For producing the diffusion transfer image the composite sheet materialis then wetted with an aqueous processing liquid in the presence ofdeveloping agents, a complexing agent for silver halide, e.g. sodiumthiosulphate, and an alkaline substance. The alkaline substance and thecomplexing agent for silver halide are preferably provided in theaqueous liquid. The developing compound(s) for silver halide, on thecontrary, (is) are preferably at least partially and even wholly presentin the photographic material as described above. The processing liquidpreferably has a rather low viscosity and is a mere aqueous soluion. Itmay be applied according to whatever technique usual in the art, e.g. bydipping the composite sheet material in it, by means of a licking rolleretc. It may contain all kinds of additional ingredients, e.g. heavymetal ions-sequestering agents, and anti-silver sludge agents,stabilizers, image-tone improvers, wetting agents, etc.

After a very short processing time, an excellent diffusion transferimage becomes visible through the support. The following exampleillustrates the present invention.

EXAMPLE Both sides of a cellulose triacetate film support having athickness of 0.1 mm. were coated with a gelatin subbing layer.

One side of the resulting subbed film support was provided with a matlayer from the following coating composition in a ratio of 10sq.m./litre:

Water ml 500 Silica g 140 Gelatin g 70 Water up to 1000 ml.

The other side of the subbed film support was coated successively withthe following layers:

An image-receiving layer obtained by applying the following coatingcomposition at a ratio of 30 sq.m./litre:

Water ml 820 Gelatin g 60 Dispersion of silver sulphide in an aqueoussolution of gelatin (0.2% of silver sulphide and 11.6%

of gelatin) ml 30 A 1% solution of l-phenyl-5-mercaptotetrazole inethanol ml 1 1-pheny1-3-pyrazolidinone g 5 12.5% aqueous solution ofsaponin ml 30 Water to 1000 ml.

A pigment layer obtained by applying the following coating compositionat a ratio of 10 sq. m./litre:

Water ml 603 Titanium dioxide g Gelatin g 4.8 Propylene glycol ester ofalginic acid g 17.2 12.5% aqueous solution of saponin ml v 25.8 20%aqueous solution formaldehyde ml 4.3

Water to 1000 1111.

diffusion transfer copies, this apparatus containing the followingalkaline processing liquid:

Water ml 1000 Sodium phosphate g 75 Anhydrous sodium sulphite g-- 40Anhydrous sodium thiosulphate g A high quality diffusion transfer imagebecame visible through the cellulose triacetate support. The maximumreflex density of this image amounted to 1.5. The maximum reflex densityof the negative image at the emulsion side amounted to 0.5.

The negative image was not visible at the side of the support because itwas screened from view by the pigment layer.

We claim:

1. A composite integral light-sensitive diffusion transfer photographicsheet material for copying originals comprising in successive order aflexible transparent support sheet, and image-receiving layer comprisingdevelopment nuclei, a pigment layer containing an opaque white orcolored pigment dispersed in an exterior hydrophilic colloid binder,wherein the pigment and the binder of the pigment particles are presentin amounts of from 7 to g. per sq. m. and of from 0.5 to 4 g. per sq. m.respectively, and a light-sensitive silver halide emulsion layer, themaximum developed reflex density of which is equal to or lower than 0.8.

2. A photographic material according to claim 1, wherein the imagereceiving layer is a gelatin layer comprising heavy metal sulphidedevelopment nuclei.

3. A photographic material according to claim 1, wherein the pigmentparticle sof the pigment layer are barium sulphate and/or titaniumdioxide pigment particles.

4. A photographic material according to claim 1, wherein the binder ofthe pigment layer comprises gelatin.

5. A photographic material according to claim 1, wherein the binder ofthe pigment layer comprises gelatin and a hydrophilic colloid being alatent hardener for gelatin.

6. A photographic material according to claim 5, wherein saidhydrophilic colloid being a latent hardener for gelatin is a propyleneglycol ester of alginic acid.

7. A photographic material according to claim 1, wherein the pigmentlayer contains an amount of pigment particles of from 10 to 20 g. persq. rn. and an amount of hydrophilic colloid binder of from 1 to 3 g.per sq. m.

8. A photographic material according to claim 1, wherein the rear sideof the photographic material is provided with a matting layer.

9. A photographic material according to claim 1, wherein the compositesheet material comprises a developing agent.

10. A photographic material according to claim 9, wherein the compositesheet material comprises hydroquinone and/or a 3-pyrazolidinone:developing agent.

11. In a method of reproducing an original by the photographic diifusiontransfer process comprising the steps of image-wise exposing a compositeintegral photographic light-sensitive sheet material and subsequentlytreating this material in the presence of photographic developing agent,a complexing agent for silver halide, and an alkaline substance, with anaqueous processing liquid, the improvement wherein said photographiclightsensitive composite sheet material comprises in successive order aflexible transparent support sheet, an imagereeciving layer comprisingdevelopment nuclei, a pigment layer containing an opaque white orcolored pigment dispersed in a hydrophilic colloid binder, wherein thepigment and the binder of the pigment particles are present in amountsof from 7 to 25 gpper sq. m. and of from 0.5 to 4 g. per sq. m.respectively, and an exterior light-sensitive silver halide emulsionlayer, the maximum developed reflex density of which is equal to orlower than 0.8, and said composite material is exposedreflectographically through said transparent support sheet while saidoriginal is disposed in direct contact with said emulsion layer, wherebythe copy of the original when viewed through said transparent supportsheet is a right reading positive of said original.

12. A method according to claim 11, wherein the total amount of thephotographic developing agent is present in the photographic compositesheet material and the aqueous processing liquid is an alkaline liquidsubstantially free of any developing agent.

References Cited UNITED STATES PATENTS 2,692,830 10/1954 Land 96-29 R2,563,342 8/1951 Land 96-29 X 3,335,007 8/1967 DeHaes 96-29 3,245,7914/1966 Ryan 96-29 3,053,745 9/1962 Levinos 9629 X 3,042,514 7/ 1962 Roth9629 3,021,214 2/1962 Murphy et a1. 9629 NORMAN G. TORCHIN, PrimaryExaminer I. L. GOODROW, Assistant Examiner U.S. Cl. X.R. 9676 C, 47

, Attesting Officer Dated June 19, 1973 Patent No 3,740 ,220

lnventofls) Louis Maria DE HAES et ,1

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 5, Claire 1, line 20, cha nge "and" to an line 22, change "anexterior" to a line 26 oh ang e "and e" to and an exterior i Q Signedarid sealed this 22nd day of January 19714..

(SEAL) At test:

EDWARD 1V1}. FLE'TCHEEJE, RENE D. TEGTMEYER Acting Commissioner ofPatent

